Support apparatus with gel layer

ABSTRACT

Apparatuses for supporting at least a portion of the body thereon, including a mattress or a mattress topper, include a polyurethane gel layer overlying at least one support layers in a foam material. The gel layer has a hardness of 4.5 kPa±1.5 kPa and a hysteresis of about 40%±10%. The gel layer faces a user, such that the gel layer confers objective and subjective comfort at the same time.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/663,826, filed Mar. 21, 2005, which is incorporated by referenceherein in its entirety. This application is a Continuation in Part ofpending U.S. application Ser. No. 11/365,473, filed on Mar. 1, 2006,incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention is generally directed to apparatuses designed forbodily support. In particular, the invention is directed to mattresses,or mattress toppers, that provide an improved level of objective andsubjective comfort, particularly pressure relief, as well as improvedcontrol of heat transfer.

BACKGROUND

Multiple apparatuses are known in the art for providing support to thebody of a user. Such apparatuses generally comprise one or more layersof padding or cushioning to provide functional support of the user'sbody and to provide such support while also providing a level ofcomfort. Similarly, such apparatuses may also comprise mechanicalsupports, such as coil springs.

Advances in the art are generally directed to apparatuses that providethe functional support necessary in such apparatuses but also provideincreased comfort or provide a decrease in the volume of materialsnecessary to provide the support. For example, U.S. Pat. No. 6,701,556to Romano et al. discloses mattress or cushion structures designed toimprove pressure distribution while reducing the overall thickness ofthe mattress or cushion. Further, U.S. Pat. No. 6,804,848 to Rosediscloses an air support sleep system having an upper mattress airposturizing module and an adjustable air posturizing sleep surface.

While the apparatuses commonly used for bodily support may providefunctional support, they yet fail to provide a level of comfort usefulfor facilitating restfulness or sleep, or for providing a greatestrelief of pressure for the body parts in contact with the supportsurface. Gel materials are generally known to provide good physicalcomfort and pressure relief. Further, gels are also known to exhibit arelatively high thermal conductivity. Accordingly, gels, such aspolyurethane gels, are generally regarded as having a “cool” feel to thebody, as body heat is perceptibly moved away from the body when incontact with the gel. The US 2004/058163 application teaches using corkto adjust gel hardness, in particular for shoe soles. Further, the gelsexemplified in this application have a Shore L hardness 46 or of 55, 62,and 53, as indicated in the comparative tests of this application, thatcorrespond to a hardness above 100 kPa at 40% compression on forcedeflection.

Accordingly, there still remains a need in the field for apparatusesuseful for bodily support, such as mattress or mattress toppers, thatprovide functional support to the body of the user, as well as providingsubjective and objective comfort and therapeutic benefit. Suchproperties, as well as further desirable and beneficial properties, aremet by the present invention.

SUMMARY OF THE INVENTION

The present invention provides an apparatus for supporting at least aportion of the body thereon. In particular, the apparatus is a mattress,or a mattress topper. Beneficially, the apparatus comprises a gel layercomprising a gel having a measurable hardness in a specified range.Furthermore, the apparatus comprises a plurality of layers, andpreferentially, the layers comprise at least two different types ofmaterials, one layer of the apparatus comprising a gel. The apparatus ofthe invention is beneficial for improving pressure mapping and providingpressure relief, and it also provides the ability to absorb andtransport heat.

In one embodiment of the invention, the apparatus comprises a gel layeroverlying one or more additional support layers. According to thisembodiment of the invention, the gel layer comprises a gel havingspecific physical properties identified as providing increased supportpressure and relief to a user, and also providing a user with anincreased perception of comfort (i.e., a good “feel”). The gel layer isthe outermost layer of the apparatus, facing the user. According tofurther embodiments, the apparatus can also comprise a coveringoverlying the gel layer. However, the covering layer is not of structureor thickness to substantially reduce or mask the comfort and supportprovided by the gel layer. Non-limiting examples of coveringsencompassed by the invention include a textile layer, a film layer, acoating layer, and a foam layer.

The gel used in the gel layer of the apparatus is particularlyformulated to exhibit physical properties, such as hardness andelasticity, that are within a range that not only provide a good “feel”,or increased comfort, to a user but also provide increased support andpressure relief beneficial to the user. In one particular embodiment,the gel used in the gel layer has a measurable hardness in the range ofabout 0.5 kPa to about 50 kPa. In another embodiment, the elasticity ofthe gel is measurable in terms of hysteresis, the hysteresis percentageof the gel being in the range of about 15% to about 80%.

The one or more additional support layers used in the apparatus caninclude any type of support material generally known in the art ofbodily support apparatuses, particularly in the art of mattresses andseating apparatuses. For example, the one or more additional supportlayers may include one or more of the following: a foam layer, a springlayer, a textile layer, a gas layer, a wood layer, a metal layer, and aplastic layer. Accordingly, the apparatus of the invention finds use ina wide variety of supports. For example, the apparatus of the inventioncould be used for supporting the entire body or only a portion of thebody. As such, the inventive apparatus finds use in home settings, suchas bedding or seating, in office settings, such as chair seats, chairback rests, chair arm rests, keyboard wrist rests, and the like, intransportation, such as car seats or other interior components, medicalsettings, such as bedding, wheelchairs, and clothing, particularlyfootwear, as well as other settings wherein comfort or pressure reliefare to be maximized. In one particular embodiment, the apparatus is amattress. Non-limiting examples of support apparatuses encompassed bythe invention include seating apparatuses, pillows, mattress toppers,mattresses, footwear cushions (or insoles), arm pads, and wrist pads.

According to another embodiment, the gel layer, in addition to the gel,may further comprise a content of one or more fillers. Such fillers areparticularly useful in modifying the thermal conductivity of the gelused in the gel layer. As previously noted, gels are typically by a“cool” feel, in part arising from the thermal conductivity of the gel inthat it transports heat away from a warmer object in contact with thegel, such as the body of a user. The fillers used in the gel layer arepreferentially capable of reducing the thermal conductivity of the gel,thereby allowing the gel to exhibit a feel to a user that is less“cool”.

Various types of filler can be used according to the invention. Thefiller material should generally be nonreactive with the gel, or withpossible derivatives of the gel or the precursors thereof (e.g.,isocyanates and polyols in the case of polyurethane gels). Preferably,the filler is a material capable of beneficially affecting one or morephysical characteristics of the gel including, but not limited to, thethermal conductivity of the gel. In one particular embodiment of theinvention, the filler material is selected from the group consisting ofcork pieces, cork flour, wood pieces, wood chips, foam flakes, textilefibers, textile pieces, paraffins, hollow spheres, synthetic microspheres, mineral particles, glass beads, gasses, active agents,nanoparticles, and mixtures thereof.

In one particular embodiment, there is provided an apparatus forsupporting at least a portion of the body thereon, the apparatuscomprising a filled gel layer overlying one or more additional supportlayers. Preferentially, the filled gel layer has a thermal conductivityof less than about 0.20 W·m-1·° K⁻¹.

In another aspect of the invention, there is specifically provided amattress. In one embodiment, the mattress comprises a gel layeroverlying a foam layer. Preferably, the gel layer comprises a gel havinga hardness in the range of about 0.5 kPa to about 50 kPa. In a preferredembodiment, the gel is a polyurethane gel. According to furtherembodiments, the mattress can comprise further support layers, such as aspring layer, and can also further comprise a covering, such as atextile layer.

In another embodiment, the mattress comprises a gel layer overlying aspring layer. Preferably, the gel layer comprises a gel having ahardness in the range of about 0.5 kPa to about 50 kPa. In a specificembodiment, the gel is a polyurethane gel. According to furtherembodiments, the mattress can comprise further support layers, such as afoam layer, and can also further comprise a covering, such as a textilelayer.

The mattress according to this aspect of the invention can be furthercharacterized by additional physical properties of the gel used in thegel layer. For example, in one embodiment, the gel layer comprises a gelhaving an elasticity such that the hysteresis of the gel is in the rangeof about 15% to about 80%.

In still another aspect of the invention, there is specifically provideda mattress topper. In one embodiment, the mattress topper comprises agel layer overlying a foam layer, wherein the foam layer preferably isof a thickness that is substantially less than an average thickness of astandard mattress. In one particular embodiment, the foam layer of themattress topper has a thickness of less than about 5 cm. In furtherembodiments, the mattress topper can comprise a covering overlying thegel layer. Preferably, the gel layer comprises a gel having a hardnessin the range of about 0.5 kPa to about 50 kPa. In a preferredembodiment, the gel is a polyurethane gel.

In yet another aspect of the invention, there is specifically provided apillow. In one embodiment, the pillow comprises a gel layer overlying afoam layer. In one preferred embodiment, the gel layer overlies only aportion of the foam layer. Preferably, the gel layer comprises a gelhaving a hardness in the range of about 0.5 kPa to about 50 kPa. In apreferred embodiment, the gel is a polyurethane gel. In still furtherembodiments, the pillow can comprise a covering overlying the gel layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1 is a cross-sectional view of a mattress topper in accordance withthe present principles;

FIG. 2 is a top-down view of a mattress topper in accordance with thepresent principles;

FIG. 3 is a top-down view of a mattress topper in accordance with thepresent principles;

FIG. 4 is a top-down view of a mattress topper in accordance with thepresent principles; and

FIG. 5 is a top-down view of a mattress topper in accordance with thepresent principles.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described more fully hereinafter inconnection with preferred embodiments of the invention which are givenso that the present disclosure will be thorough and complete and willfully convey the scope of the invention to those skilled in the art.However, it is to be understood that this invention may be embodied inmany different forms and should not be construed as being limited to thespecific embodiments described herein. Although specific terms are usedin the following description, these terms are merely for purposes ofillustration and are not intended to define or limit the scope of theinvention. Like numbers refer to like elements throughout. As used inthis specification and the claims, the singular forms “a”, “an”, and“the” include plural referents unless the context clearly dictatesotherwise.

The present invention provides an apparatus useful for bodily support,particularly support that, in addition to being functional, alsoprovides increased comfort and pressure point relief for a user. Theapparatus is characterized by its use of a gel material exhibitingpreferred physical characteristics for providing a pleasing “feel” to auser, as well as therapeutic benefits.

The gel used in the apparatus of the invention can comprise any gel thatis stable, non-toxic, and generally known to provide a cushioning effectwhile maintaining a degree of structural stability and support. Inparticular, the gel can comprise any gel material having a hardness andelasticity that are within a preferred range, as more fully describedherein.

Polyurethane gels are particularly useful according to the invention.Further, other gels that are resistant to hardening over time, havelimited expandability, and are resistant to substance degradation (e.g.,from migration of volatile agents, such as plasticizers) could also beuseful as the gel in the present invention. Preferably, the gels used inthe apparatus of the invention are also shock absorbent and resistant tovibration.

Polyurethanes are generally understood to be the product of the chemicalreaction between a polyisocyanate compound and a polyfunctional alcohol(i.e., a polyol). One example of a general reaction scheme for preparinga polyurethane compound is shown below:

wherein R₁ and R₂ can be various organic groups including, but notlimited to, straight or branched chain or cyclic alkyl, alkenyl, oralkynyl groups, as well as various aryl groups. Of course, the abovescheme is provided only as an example of the preparation of thepolyurethane compounds useful according to the invention and is notintended to be limiting thereof. Additional examples of polyurethanegels capable of use according to the invention are disclosed in U.S.Pat. No. 6,191,216, United States Published Patent Application No.2004/0058163 (application Ser. No. 10/618,558) and United StatesPublished Patent Application No. 2004/0102573 (application Ser. No.10/656,778), which are incorporated herein by reference. Examples ofother types of gels useful according to the invention are disclosed inU.S. Pat. No. 4,404,296, U.S. Pat. No. 4,456,642, and United StatesPublished Patent Application No. 2005/0186436 (application Ser. No.11/058,339), which are incorporated herein by reference.

In one embodiment of the invention, the gel used in the gel layer of theapparatus comprises a polyurethane gel. Particularly, the polyurethanegel is prepared using raw materials having an isocyanate functionalityand a functionality of the polyol component, wherein the product of thefunctionalities of polyol and isocyanate is at least 5.2, but preferablyat least 6.5 or 7.5. In preferred embodiments of the present invention,the polyol component for producing the gel includes a mixture of one ormore first polyols having hydroxyl numbers below 112, and one or moresecond polyols having hydroxyl numbers in the range 112 to 600, whereinthe weight ratio of the first polyols to the second polyols lies between90:10 and 10:90, the isocyanate characteristic of the reaction mixturelies in the range from 15 to 59.81, and the product of isocyanatefunctionality and functionality of the polyol component is at least6.15.

In a further specific exemplary embodiment, the raw materials forproducing a gel useful according to the invention includes one or morepolyisocyates, and a polyol component consisting of a first component ofone or more polyols having hydroxyl numbers below 112, and a secondcomponent of one or more polyols having hydroxyl numbers in the range112 to 600, and optionally a catalyst for the reaction betweenisocyanate and hydroxyl groups, and optional fillers and/or additiveswhich are known from polyurethane chemistry, wherein the weight ratio offirst component to the second component lies between 90:10 and 10:90,the isocyanate characteristic of the reaction mixture lies in the rangefrom 15 to 59.81, and the product of isocyanate functionality of thepolyol component is at least 6.15.

The polyol component for producing the gel preferably consists of one ormore polyols having a molecular weight between 1,000 and 12,000 and anOH number between 20 and 112, wherein the product of the functionalitiesof the polyurethane-forming components is at least 5.2, and theisocyanate characteristic lies between 15 and 60.

As isocyanates for gel production, those of the formula Q(NCO)_(n) maypreferably be used, wherein n represents 2 to 4 and Q denotes analiphatic hydrocarbon radical having 6 to 18 C atoms, a cycloaliphatichydrocarbon radical having 4 to 15 C atoms, or an aromatic hydrocarbonradical having 8 to 15 C atoms. The isocyanates may be used in pure formor in the form of the conventional isocyanate modifications, such asurethanisation, allophantisation or biuretisation.

Gels, such as polyurethane gels, are particularly useful in theapparatuses according to the invention due in part to the balancedpressure distribution provided by the gel. Unlike standard paddingmaterials, which react to an applied pressure, such as a user sitting orlying of the padding, by deforming along only the axis of the appliedpressure (i.e., the axis perpendicular to the plane of the padding),gels tend to exhibit tri-dimensional deformation properties. In otherwords, the gel reacts to the applied pressure by deforming along threeaxes: the X and Y axes in the plane of the gel surface, as well as the Zaxis that lies perpendicular to the plane of the gel surface. This leadsto an even distribution of the exerted pressure, which lessens thepressure felt by the user at the pressure points. This is preferableover the standard padding materials, which allow for an uncomfortable,and possibly damaging, accumulation of pressure at the pressure points.Accordingly, in addition to providing added comfort, the gel provideshealth advantages, such as increased blood circulation, encouragement ofcorrect posture, and alleviation of pressure concentration, which canlead to serious conditions, such as bed sores, or other types ofulcerations.

Gel materials useful in the apparatus of the invention are particularlybeneficial for their ability to maximize pressure distribution, whichcan be seen through pressure mapping. Pressure mapping is a clinicaltool that measures interface pressure that occurs between a user and asupport surface, such as a seat or a bed surface. With standard supportcushions and paddings, pressure maps tend to reveal localized highpressure areas, which indicate an inability to evenly distributepressure. Gels, especially polyurethane gels, and other gels usefulaccording to the invention, are superior to standard supports because oftheir ability to distribute pressure away from pressure points, asdemonstrated by pressure maps showing lower pressure readings at thepressure points.

Gels used according to the present invention are characterized by thespecific physical properties they exhibit. Two physical properties thatparticularly characterize the gels of the invention are hardness andelasticity. Optimization of these two properties exhibited by the gelsallows for preparation of an apparatus providing both objective andsubjective comfort and support. In other words, gels according to theinvention having a certain degree of hardness and a certain degree ofelasticity provide therapeutic benefits (i.e., objective comfort), aspreviously described, but also provide a user with a good “feel” (i.e.,subjective comfort). The ability to provide both objective andsubjective comfort is particularly useful because a support apparatusdesigned to provide therapeutic benefit to a user may not always feelgood to the user. Conversely, what feels good to a user may not alwaysprovide therapeutic benefit to the user. However, gels according to theinvention having a hardness and elasticity within the presentlyspecified ranges provide both objective and subjective comfort.

The gel used in the gel layer of the inventive apparatus ischaracterized by having a low degree of hardness, such hardness beingmeasurable as the force deflection of the gel at a specific compression.Gel hardness can be measured according to any known method, and a geluseful according to the invention can be identified as having a hardnessin a specified range. One method particularly useful according to theinvention for measuring gel hardness is the testing method ISO 3386-1,as designated by the International Organization for Standardization(ISO).

According to ISO 3386-1, a method is provided for the calculation of thecompression stress value of various materials. The compressionstress/strain characteristic is a measure of the load-bearing propertiesof the material, and the testing method provides two formulas forcalculating the compression force deflection in kilopascals (kPa), whichprovides a measured hardness of the material.

Specifically, under the ISO 3386-1 standard, a gel according to theinvention can be measured for a hardness determination through acompression load deflection test. In particular, a 5 cm×5 cm×2.5 cm gelsample is subjected to a compressive force, with a 70% maximumcompression, and gel hardness is measured as the stress applied to thegel (in kPa) at 40% compression.

A gel useful according to the invention has a low measurable hardness.Preferentially, the gel has a measurable hardness that is less than 90kPa, more preferably less than 80 kPa, still more preferably less than70 kPa, and most preferably less than 60 kPa. In one embodiment, the gelused in the invention has a measurable hardness in the range of about0.5 kPa to about 50 kPa. According to further embodiments, the gel has ahardness in the range of about 1 kPa to about 40 kPa, about 1.5 kPa toabout 30 kPa, or about 2 kPa to about 25 kPa

According to another embodiment of the invention, the gel used in thegel layer of the apparatus is characterized by having a measurableelasticity that is within a specified range. In solid mechanics, amaterial is understood to behave elastically if it changes shape due toan applied load, and when the load is removed, the material recovers itsoriginal shape. The elasticity of a material is inversely proportionalto its stiffness.

One method for evaluating the elasticity of a gel for use according tothe invention is through determination of the hysteresis exhibited bythe gel. Hysteresis is a property of systems (usually physical systems)that do not instantly follow the forces applied to them, but reactslowly, or do not return completely to their original state. Hysteresis,then, can be evaluated as the ability of a material, such as a gel, toreturn to its original shape after removal of a force on the gel.

In one method for determining hysteresis, a force is applied to a gel,which leads to compression of the gel. The deflection of the force bythe gel at 70% compression is measured, and the external force isremoved, allowing the gel to decompress. The deflection of the gel underno compression (i.e., after removal of the force) is then measured.

The hysteresis of the gel (evaluated as a percentage) is the differencebetween the two force values at the defined deflections. Accordingly, agel exhibiting a low hysteresis percentage would be expected to behighly elastic, in other words, have a rapid and significantly completereturn to its original shape. A gel exhibiting a high hysteresispercentage would be expected to be less elastic, in other words have amore delayed and less complete return to its original shape.

According to the present invention, it is beneficial for a gel for usein the gel layer to be elastic, but not exhibit physical properties thatare highly temperature dependent.

For example, viscoelastic foams, commonly known as “memory foam”,typically exhibit a glass transition temperature (T_(g)) at around roomtemperature. In a cold environment, a memory foam product will tend tobe harder and less resilient. Conversely, in a warmer environment, amemory foam product will tend to be softer and more resilient.Accordingly, the product changes in response to the surroundingtemperature, including temperature changes attributable to body heatflow.

Gels useful according to the present invention, being highly elastic, donot suffer from such a drawback. Rather, the gel the gels exhibit anelasticity (or percentage hysteresis) that is not temperature dependent.In one embodiment, the gel used in the invention has a measurablehysteresis in the range of about 15% to about 80%. According to furtherembodiments, the gel has a hysteresis in the range of about 20% to about70%, about 25% to about 60%, or about 30% to about 50%.

While gels in general tend to exhibit superior pressure distributionproperties to standard cushioning materials, such as foam, gels alsotend to exhibit greater thermal conductivity than foam. High thermalconductivity can be a desirable gel property, such as in a warmenvironment where a cooling effect would be welcomed. In othersituations, however, it may be more desirable to have a lower thermalconductivity in order to conserve heat near the body of the user.Accordingly, the present invention is beneficial in that the gel used inthe gel layer of the inventive support apparatus can have a determinablethermal conductivity.

Thermal conductivity (X), which is generally reported in terms of wattsper meter per degree Kelvin (W·m⁻¹·° K⁻¹), relates to the ability of amaterial to transmit heat under fixed conditions. The lower the value ofλ, the better insulator the material will be. Conversely, the higher thevalue of λ, the better heat conductor the material will be.

Foam, a typical cushion material for support apparatuses, is known to bea material exhibiting good insulating properties. For example, moldedfoam, such as used for seat cushions, typically has a λ value of about0.04 W·m⁻¹·° K⁻¹, and foam used in construction and building materialstypically has a λ value of about 0.022 W·m⁻¹·° K⁻¹. When a highlyinsulating material, such as foam, is used in a support apparatus forhuman use, the heat generated by the human body, at first contact withthe foam, is immediately transferred to the contact surface of the foam.With time, the transferred heat finds a high resistance to movementthrough the foam for dissipation. The energy (heat) producedcontinuously by the human body generates an increase in temperaturebecause the foam is unable to absorb the energy and transport it awayfrom the contact area quickly enough. In other words, while the initialwarmth maintained by the contact with the foam may be of a comfortablelevel, an eventual heat build-up leads to discomfort for the user.

Polyurethane gels, and similar gels as described herein, exhibitdifferent thermal properties and can generally be considered goodconductors of heat compared to foam. For example, a polyurethane gel canhave a X value of about 0.20 W·m⁻¹-° K⁻¹ or greater. Polyurethane gelsalso typically have a greater density than foam. For example,polyurethane gel can typically have a density in the range of about 600to about 1,100 Kg/m³, while expanded foam for seat cushions cangenerally range from about 30 to about 85 Kg/m³. Further, polyurethanegels commonly have a high thermal capacity. This combination ofincreased ability to transport heat through the material, highermaterial mass per unit area, and high amount of energy needed toincrease the material temperature makes a significant difference on thetype of exchange of heat from the user to the gel over time.

The heat exchange capacity of the gels used in the gel layer accordingto the invention therefore further contributes to the good “feel” usersdesire and appreciate in a support apparatus, such as a mattress,pillow, seating apparatus, or the like. Accordingly, the presence of thegel layer allows for increased comfort not only because of the pressuredistribution qualities of the gel but also because of the thermalconductivity of the gel and the corresponding ability to move heat awayfrom the body and therefore circumvent the eventual heat buildupassociated with many support apparatuses that can lead to discomfort.

Beneficially, gels useful according to the invention can have their λvalues altered through addition of one or more fillers. Filled gels areuseful according to the invention because they can be used in a supportapparatus to provide increased comfort and pressure distribution, aspreviously noted, while also having a lower thermal conductivity tolessen the movement of heat away from the body of the user. Suchlowering of the A value of the gel reduces the “coolness” of the gel.This can also increase the subjective comfort of the support apparatusfor users who desire a feeling of warmth.

Accordingly, in one embodiment of the invention, the gel used in the gellayer of the support apparatus further comprises one or more fillers.The filler material can be any material capable of admixture with thegel and that is effective for altering the λ value of the gel. In aspecific embodiment, the filler material is effective for lowering the Avalue of the gel to at least a value indicative of a thermalconductivity wherein a perception of coolness of the gel is reduced. Inyet another embodiment, the filler material is effective for loweringthe λ value of the gel such that there is a perception of wan nth fromthe gel. Accordingly, various types of materials ranging from solids toliquids may be used as filler for the gel used in the gel layeraccording to the invention.

In one embodiment of the invention, the filler comprises a solidmaterial. Preferentially, the solid material comprises a particulatematerial. The average size of the particulate can vary depending uponthe apparatus in which the filled gel is to be used and can also varydepending upon the value desired in the filled gel. In one embodiment,the filler can comprise coarse particles. In another embodiment, thefiller can comprise fine particles (i.e., powders). In yet anotherembodiment, the filler can comprise nanoparticles. In a particularembodiment of the invention, the filler material comprises particulateshaving an average diameter of about 0.05 mm to about 15 mm. In anotherembodiment, the particulates have an average diameter of about 0.10 mmto about 10 mm, about 0.10 mm to about 5 mm, or about 0.10 to about 1mm.

In another embodiment of the invention, the filler material compriseshollow material, such as microspheres. Such hollow material can benatural or synthetic in origin, but are generally expected to besynthetically produced material. For example, the material can comprisesynthetic microspheres. Such micro spheres are preferably formed from apolymer material such as a polyolefin, particularly an acrylonitrilecopolymer or polyvinylchloride. In addition to the synthetic microspheres, other types of hollow materials having various geometries couldalso be used in the filled gel. For example, in addition to hollowmaterials that are generally spherical in nature (also described asbeing balloon-like), the hollow materials can also be in the form oftubular, rectangular, or other geometric shapes.

In another embodiment of the invention, the filler comprises a liquid,particularly an organic liquid. The liquid is preferably chemicallyinert to the gel used in the gel layer, as well as starting materials,intermediates, and by-products in the preparation of the gel (such asisocyanates and polyols in the case of polyurethane gels). Accordingly,the liquid filler is generally preferably selected from materials, suchas plasticizers (including oils, resins, and hydrocarbon derivatives),hydrocarbons and fuels, alkylbenzenes, and liquid esters. Moreparticularly, the liquid material can include amorphous orsemicrystalline paraffins, naphthenic oils or resins, heavy and lightfuels, alkylbenzenes, esters (preferentially products of polyhydricalcohols with monobasic carboxylic acids), alkylpolyaromatic compound,and vegetable oils, as well combinations of the above liquids.

According to a further embodiment of the invention, the filler cancomprise one or more gasses. For example, the filler can compriseambient air. In other embodiments, the gas used as the filler materialcan comprise substantially pure gasses, such as nitrogen gas, or anotherinert gas, such as argon gas. The gas can also comprise gaseouscompounds, such as carbon dioxide gas.

In still another embodiment of the invention, the filler can compriseone or more active agents. As used herein, active agents are intended torefer to any additive capable of providing a therapeutic benefit to auser. For example, the active agent can include vitamins, minerals,essential oils, perfumes, and the like.

The filler generally can comprise natural or synthetic materials. Forexample, the filler can comprise natural materials, such as cork, wood,sponge, natural fibers (e.g., cotton, wool, etc), minerals (e.g., mica,or other silicates, or other metal oxides, such as aluminates), pumice,and glass (including fibers, beads, etc.). Examples of syntheticmaterials useful as fillers in the present invention include syntheticfibers, synthetic microspheres, and various other synthetic materials.In one particular embodiment of the invention, the filler is selectedfrom the group consisting of cork pieces, cork flour, wood pieces, woodchips, foam flakes, textile fibers, textile pieces, paraffins, hollowspheres, synthetic microspheres, mineral particles, glass beads, gasses,active agents, nanoparticles, and mixtures thereof.

The content of filler present in the gel can vary depending upon theapparatus in which the filled gel is to be used and can also varydepending upon the A value desired in the filled gel. In one embodimentof the invention, the filler comprises about 5 percent to about 95percent of the filled gel, on a volume basis. In another embodiment, thefiller comprises about 10 percent to about 90 percent of the filled gel,on a volume basis. In still another embodiment, the filler comprisesabout 20 percent to about 80 percent of the filled gel, on a volumebasis. In yet another embodiment the filler comprises about 25% to about75% of the filled gel, on a volume basis.

Depending upon the type of filler used in the filled gel and the contentof the filler in the filled gel, the λ value of the filled gel can bealtered from the λ value of the gel without the filler. Preferably, thepresence of the filler in the filled gel causes the filled gel toexhibit a reduced X value. In other words, it is preferable for thefilled gel to have a thermal conductivity that is less than the thermalconductivity of the gel without the filler.

In one embodiment of the invention, the filled gel has a thermalconductivity of less than about 0.20 W·m^(−1 SM)° K⁻¹. In anotherembodiment, the filled gel has a thermal conductivity of less than about0.15 W·m⁻¹·° K⁻¹. In still another embodiment, the filled gel has athermal conductivity of less than about 0.10 W·m⁻¹·° K⁻¹. In oneparticular embodiment of the invention, the filled gel has a thermalconductivity of less than or equal to about 0.08 W·m⁻¹·° K⁻¹.

In addition to the gel layer (which may or may not include one or morefillers), the support apparatus of the invention can further compriseone or more additional support layers underlying the gel layer. Theadditional support layer can include any type of material generallyrecognized in the art as being useful for providing support to at leasta portion of the body of a user. For example, the additional supportlayer can comprise a layer of foam, which can take on any of the variousembodiments generally useful for providing a cushioning effect or asupportive effect. The additional support layer can also comprisesprings, which are recognized as being useful for providing support tothe body. The layer of springs can take on any embodiment known in theart for providing effective support while also providing comfort for theuser. For example, the spring layer can comprise a series of springsthat are at least partially interconnected. Furthermore, the springlayer can comprise a series of springs that are present as separatecoils. Further additional embodiments of spring layers are alsoencompassed by the present invention, which is not intended to belimited by the examples provided above. For example, the invention alsoencompasses apparatuses wherein the additional support layer comprisesother materials known for providing support, including gas (such asair), cushioning materials, or paddings, textile layers, and alsoincluding materials providing structure, such as wood, metal, or rigidplastics.

In one embodiment of the invention, the support apparatus comprises agel layer and at least one additional support layer of a foam material.In another embodiment of the invention, the support apparatus comprisesa gel layer and at least one additional support layer of springs. Instill another embodiment of the invention, the support apparatuscomprises a gel layer, at least one additional support layer of springs,and at least one additional support layer of a foam material. In oneparticular embodiment of the invention, the one or more additionalsupport layers are positioned underlying the gel layer such that thereare no additional support layers positioned above the gel layer.

The additional support layers and the gel layer can be integrallyattached or can be separate bodies. By integrally attached is intendedto mean the layers are attached one to another by means such that thetwo layers are not separable without at least partially damaging one ormultiple layers. For example, the layers may be integrally attached,such as by gluing, stapling, sewing, welding, or the like. Further, thelayers may be integrally attached through chemical bonding. For example,when the gel layer comprises a polyurethane gel and the additionalsupport layer comprises a polyurethane foam, both layers have freeisocyanate groups prior to curing (or maturation) of the gel or foam.Accordingly, a when one layer is allowed to cure while adjacent theother layer, chemical bonding between the gel and the foam can occur.

Foam support layers are particularly useful in combination with a gellayer, not only because of ease of bonding, as described above, but alsobecause of the various combinations provided. For example, in oneembodiment, convoluted foam may be used. In another embodiment, the foammay have one or more cavities for receiving all or part of the gellayer. When such cavities are present, the cavities may be on a “top”surface of the foam, a “bottom” surface of the foam, or on both a topand bottom surface of the foam.

In specific embodiments of the invention, where the additional supportlayer comprises a foam layer, it can be particularly useful for the foamlayer to be of a specified thickness. For example, where the apparatusis relatively large and the foam layer provides a substantial amount ofthe structure of the apparatus, such as in mattress, it can bebeneficial for the foam layer to be of a substantial thickness. Forexample, in one embodiment, the additional support layer comprises afoam layer having a thickness of at least about 5 cm. In furtherembodiments, the foam layer has a thickness of at least about 6 cm, atleast about 7 cm, at least about 8 cm, at least about 9 cm, and at leastabout 10 cm.

In other embodiments of the invention, it may be preferred for theadditional support layer to be of a lesser thickness than as describedabove. For example, when the support apparatus is a shoe insert, it isdesirable for the apparatus to have a minimum thickness. Likewise, inembodiments wherein the apparatus is a mattress topper, it is beneficialfor the additional support layer to have a minimum thickness to avoidadding to the overall profile of the mattress topper. For example, inone embodiment, it is beneficial for the additional support layer to bea foam or textile layer having a thickness of less than about 5 cm. Infurther embodiments, the additional support layer preferably has athickness of less than about 4 cm, less than about 3 cm, and less thanabout 2 cm.

In addition to the gel layer and the additional support layer or layersas described above, the support apparatus of the invention alsoencompasses the addition of a covering overlying the gel layer. Thecovering can generally comprise any type of material commonly used incoverings for the various types of support apparatuses encompassed bythe invention. Such coverings include natural and synthetic materials.Further, such coverings can also include padding. For example, when thesupport apparatus is a mattress, the covering can be a padded mattresstopper. Further, any type of upholstering material can be used as thecover in the present invention. Accordingly, the presence of the gellayer in no way limits the types of covers available for use in coveringthe support apparatus of the invention. Furthermore, other types ofcoverings are also encompassed by the invention. For example, thecovering can comprise a film, such as a polyurethane film, a coating,such as a polymer that is non-reactive or non-tacky in a dried or curedstate, or a foam.

As with the additional support layer, in certain embodiments of theinvention, it may be beneficial for the covering layer to be of aspecific thickness. Generally, the covering layer should be of minimalthickness to avoid masking the therapeutic benefits and pleasing feel ofthe gel layer. For example, in one embodiment, the covering comprises afoam layer. According to this embodiment, it is preferable for the foamlayer to have a thickness of less than about 5 cm. In furtherembodiments, the covering preferably has a thickness of less than about4 cm, less than about 3 cm, and less than about 2 cm.

The presence of the gel layer in no way limits the scope of supportapparatuses encompassed by the invention. Accordingly, the supportapparatus of the invention can include apparatuses, such as mattresses,chairs, sofas, recliners, wheelchairs, pillows, furniture cushions,office equipment, automobile parts, mattress toppers, and the like. Inone particular embodiment of the invention, the support apparatuscomprises a bed mattress. In another embodiment of the invention, thesupport apparatus comprises a seating apparatus. In still anotherembodiment, the support apparatus comprises a pillow. In still anotherembodiment, the support apparatus comprises a mattress topper.

The support apparatus of the invention comprising a gel layer overlyingat least one additional support layer, such as a foam layer and a springlayer, derives benefit from multiple aspects of the invention. Aspreviously noted, the gel layer provides an improved pressure mappingfor the various individuals that may use the support apparatus (i.e.,the gel provides improved distribution of the pressure out and away fromthe pressure points). Furthermore, the gel has the capability to absorband transport heat with different parameters than other known supportmaterials, such as foam, which generally acts as an insulator and trapsheat against a user. The gel layer in the apparatus of the invention,however, can further comprise one or more fillers and can therefore bemade according to predefined specifications to have a λ value such thatthe perception of heat flow from the body of the user is optimized forcomfort. In other words, the filled gel layer can provide a perceptionof warmth often desired by a user but not act as a heat trap, such asfoam. Further, when used in combination with further layers, such asfoam or springs, the various benefits of the gel layer can be providedwith only a relatively thin gel layer, while the bulk of the supportapparatus can comprise more conventional materials.

EXPERIMENTAL

The present invention is more fully illustrated by the followingexamples, which are set forth to illustrate the present invention andare not to be construed as limiting.

Example 1 Determination of Gel Mechanical Properties

The mechanical properties of multiple polyurethane gels useful accordingto the present invention were determined using testing methods asdescribed herein. The various gel samples were evaluated in terms ofhardness and hysteresis, and the evaluation results are provided inTable 1.

TABLE 1 Gel Mechanical Properties Sample Hardness Hysteresis ID (kPa)(%) Filler Shape Use 1 7.6 37.4 None Regular Mattress 2 6.0 35.0 NoneCylinder Mattress 3 4.4 45.7 None Cylinder Mattress 4 12.0 46.0 CorkCylinder Mattress 5 9.7 36.0 Microspheres Cylinder Seat 6 7.9 71.0 NoneRegular Seat 7 11.0 63.0 None Regular Seat 8 41.0 47.0 None RegularArmpad 9 16.0 68.0 None Regular Armpad 10 3.1 54.5 None Tower Mattress11 32.6 51.1 None Tower Armpad 12 92.0 63.0 None Regular —

For each gel sample, the sample shape, optional filler material,exemplary use, hardness (measured as force deflection at 40%compression), and percent hysteresis are provided. For sample shape,“regular” indicates a sample 5 cm wide×5 cm long×2.5 cm thick,“cylinder” indicates cylindrical sample having a diameter of 5 cm andbeing 3 cm thick, and “tower” indicates a sample 5 cm wide×5 cm long×1.7mm thick having four square projections arising from the top thereof,each being 2 cm wide×2 cm long×0.8 cm thick. The use provided for eachsample is only provided for purposes of example and should not beconstrued as limiting thereof. Sample ID 12 is provided as a comparativeexample of a gel that would not be useful according to the invention,the hardness of the gel being outside the preferred range.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teaching presented in theforegoing descriptions. Therefore, it is to be understood that theinventions are not to be limited to the specific embodiments disclosedand that modifications and other embodiments are intended to be includedwithin the scope of the appended claims. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

Example 2

Six different mattress combinations were tested. In each case, a gelsheet 79 cm×77 cm×1.5 cm was laminated over a foam layer having adensity of 30 Kg/m³ and hardness of 2 kPa and dimensions of 83 cm×104cm×1.5 cm.

The combination was positioned over a block foam having the same densityand hardness but having dimensions of 200 cm×80 cm×10 cm. The propertiesof the test gels are provided below.

TABLE 2 ID Hardness Hysteresis TGI0525 3.1 KPa  45.7%   RE30 11 KPa 63%RE40 41 KPa 68% BTG 91 KPa 63% TGI0710 98 KPa  1% TGI0711 43.9 KPa  2.4% 

The test method had five people of different height, weight, and gender,without any orthopedic pathologies to lie back on the mattress for fiveminutes. During this time, pressure distribution was tested using anXsensor X5 sensor map apparatus from X-Sensor Technology Corporation(Calgary Alberta Canada). This particular instrument uses software thatseparates the total sensor input into a number of individual sensorreadings depending upon the pressure distribution. In other words, whenthe body pressure is widely distributed across the gel, a higher numberof individual sensor readings are provided. In comparison, when the bodypressure is less widely distributed across the gel, a lesser number ofindividual sensor readings are provided. For testing purposes, thepressure of 36 mmHg was set as the benchmark for pressure discomfort.

This value is reported by Landis, E M, (1930) “Micro-injection studiesof capillary blood pressure in human skin”, Heart, 15:209-228.Capillaries are closed above this pressure threshold, and blood thusdoes not reach the external skin layers, resulting is discomfort.Evaluation was thus a count of the total number of sensors thatregistered a pressure above this limit.

For each test subject, raw data had been evaluated to establish multipleevaluations of the test materials. First, considering the total numberof sensors used, the total area of contact of the same person had beencompared across the gel layer of each test material. The greater thetotal area of contact, the better the weight distribution of the personacross the gel. Better weight distribution is a good indicator of bettercomfort and is therapeutic since it leads to less pressure at anyonegiven point.

Second, the maximum peak pressure value had been evaluated at any pointacross the gel layer. This closely follows the hardness values of thegel.

Third, the total percentage of sensors registering a pressure above the36 mmHg threshold had been evaluated. As noted previously, bloodcapillaries are closed above this value resulting in reduced blood flowor no blood flow to the skin. A high percentage of sensor readings abovethis threshold indicates a high level of objective discomfort, and aperson would automatically be induced to change position to opencapillary flow. This is the type of mechanism underlying multipleposition changes during sleeping, which correlates to sleep that is notrestful.

Fourth, the average pressure on the body for each gel layer had beenevaluated. Less overall pressure correlates to a better subjectivecomfort.

Accordingly, with the above testing procedure, a real-life evaluation ofthe subjective and objective comfort provided by the present inventivecombination had been established.

For each of the five test subjects, only sample TGI0525 consistentlyprovided the benchmark for subjective and objective comfort. SamplesRE30, RE40, BTG, TGI0710, and TGI0711 provided worse results, thesesamples having hardness and/or hysteresis values outside of theidentified ranges needed to provide the necessary subjective andobjective comfort. It was surprising to find that simple and littlevariations in hardness and hysteresis could result in changes to one orboth of subjective or objective comfort, sometimes depending upon thespecific subject being tested.

The support apparatus of the invention arises from the discovery that anapparatus, such as a bed, can be comfortable and provide therapeuticbenefit by using a specific combination of materials. In particular, theinvention comprises a bed formed of a foam mattress and a layer of gelmaterial overlying the foam mattress. Gels by themselves pose problemsfor forming beds. They are heavy in bulk and need a base support inorder for the beneficial properties of the gels to become evident. Knowntypes of supports, e.g., beds, such as foam mattresses, cotton batting,or box springs, by themselves do not provide therapeutic support.Rather, known types of supports emphasize pressure points. Thedevelopment of the present invention is based on the discovery that thecombination of a gel layer with a traditional support layer combined theadvantages of the known supports, e.g., ease of manufacture, lightweight, with the advantages of the gel layer, e.g., good comfort andtherapeutic benefit.

The concept of “comfort” has been discovered, through much testing, asnot a simple matter. It included two components: 1) subjective comfort;and 2) objective comfort. Subjective comfort can be described as a “goodfeel” and can change from person to person. For example, while someindividuals prefer a soft bed, others prefer a firm bed. Moreover, eventhe terms soft and firm can take on multiple definitions. Accordingly,one goal of the invention was to provide a support apparatus, such as abed, that would provide a good feel to a wide range of users.

Objective comfort differs from subjective comfort. Objective comfort canbe described as therapeutic comfort. This is the type of comfort that isnot necessarily sensed by the body but is reflected in the overalleffect on the body, such as improved sleep, improved relief of pressurepoints, and the like. Usually, apparatuses that provide this type oftherapeutic benefit do not also provide the good feel a user wants.Accordingly, another goal of the present embodiments is to provide amattress providing therapeutic benefit, or objective comfort, inaddition to subjective comfort. Only the combination of features of thepresent invention has allowed that, among a very large number ofpossible combinations.

However, simply combining a gel with a foam mattress did not result inthe desired effect. In fact, gel formulations were highly varied andprovided a great number of different properties. Through testing, it hasbeen determined that two properties, hardness and elasticity (orhysteresis) were crucial to providing a final combination product, i.e.,the combination of the gel layer and the underlying support layer, thatexhibited the correct values of hardness and hysteresis to provide bothsubjective comfort and objective comfort.

Likewise, prior to the present invention, no mention or suggestion waspresent to indicate that these two physical properties could be relatedto a gel structure to evaluate the support benefits of the gel.Accordingly, the present invention is the first realization that a gelhaving a hardness within a specific range and a hysteresis within aspecific range could provide this combined subjective and objectivesupport effect, particularly in consideration of the presence of theunderlying support layer as well.

Specific tests have evaluated the correct value ranges for hardness andhysteresis. The test was a comparison of pressure distribution of a gelsheet used as a topper in a mattress construction, see Example 2 above.As evident from Example 2, arriving at the specifically claimed rangesof hardness and hysteresis is not simply a matter of routineoptimization. No one previously recognized that these two propertieswere crucial to providing both subjective and objective comfort to auser. Moreover, the gel layer is provided as overlying another supportlayer. Therefore, the specified ranges of hardness and hysteresis arevalues that also depend upon the underlying support layer. In otherwords, in light of this discovery, one of skill in the art could now usethis invention as the starting point to find the best hardness andhysteresis values within our claimed ranges to match a gel with aspecific type of underlying support layer, e.g. foam, wood, cotton, etc.

These ranges are crucial to provide a combination apparatus that, for awide variety of users with subjectively rate, is comfortable andsimultaneously provides objective comfort by properly distributingpressure to avoid capillary closure. It was surprising to find thatsmall alterations in these properties can drastically affect thecritical capillary closure pressure

Referring now to FIG. 1, a cut-away view of an embodiment of the presentprinciples is shown. A gel layer 100 of a mattress or mattress topper isshown. According to one embodiment, the gel layer 100 has a thickness ofabout 8-15 mm may be formed with a hardness of 4.5 kPa±20-33% at 40%compression and an elasticity of 40%±10-20%. Moreover, the gel layer 100on the surface facing the user may be smooth or comprise a contouredsurface. For example, the surface may include a plurality of smalltowers 102 of one or more shapes that arise from the planar surfacethereof, separated by a gap 104. In this way, the small towers 102 canhelp in the tridimensional deformation of the gel and the supportapparatus itself under the weight of the user. Moreover, small towers102 are separated the one from the other by channels 104 free ofmaterial, having a width of about 4-6 mm that allow a free circulationof air in order to improve the ventilation of the surface of the supportapparatus facing the user. As an additional advantage, the gelsdescribed above, with the above-indicated hardness values, have a viablelifespan double that of conventional gel layers. A compact, not-expandedmaterial, as the gel of the present invention, with the above-indicatedhardness values was previously not considered suitable for life spanneeded for mattresses. However, tests were carried out and the mattressof the present invention had doubled the requested cycles.

It should be understood that the hysteresis and subjective and objectivecomfort are provided by a combination of gel properties and surfacefeatures and textures of the gel surface. The tower structures 102include a top surface 106 that extends a height above a lower surface108 of the gel layer 100. The tower structures 102 include athree-dimensional shape configured to have an area of the top surface106 to be much larger than an area of the lateral sides 110 of theperimeter of the tower structure 102. In this way, the large surfacearea of the top surface 104 engages a portion of the body and iscompressed. The compression is absorbed by bulging of the lateralsurfaces 110 but a large contact area is maintained with the body toensure that the contact pressure remains low. In this way, subjectiveand objective comfort is maintained. The gel layer 100 may include towerstructures 102 having a square shape, a rectangular shape, a circularshape, etc. The area ratio of the top area 106 versus the lateral area110 is preferably 3:1 or greater. The lateral sides 110 are preferablyperpendicular to the lower layer surface 108 to permit bulging. Inaddition, other shapes may be employed including, e.g., where longparallel plateaus of the towers 102 extend along the gel layer 100.These structures may be linear, zig-zag, curvy, etc.

Referring now to FIG. 2, a top-down view of an embodiment of the presentprinciples is shown, including a surface pattern of squares. The towerstructures 102 have a square cross-section and completely cover the gellayer 102.

Referring now to FIG. 3, a top-down view of an embodiment of the presentprinciples is shown, including a surface pattern of hexagons. The towerstructures 102 have a hexagonal cross-section, and towers 102 ofpartial-hexagonal cross-section may be used to fill the pattern alongthe edges, where full hexagons may not fit.

Referring now to FIG. 4, a top-down view of an embodiment of the presentprinciples is shown, including a surface pattern of circles. The towerstructures 102 have a hexagonal cross-section. Due to the curvilinearform of the towers 102, the gap 104 between towers 102 will vary insize. If a large gap is undesirable, towers 102 having a smallercircular cross-section may be formed in the gaps 104.

Referring now to FIG. 5, a top-down view of an embodiment of the presentprinciples is shown, including a surface pattern of zig-zag plateaus102. The tower structures 102 are shown as being continuous plateausseparated by gaps 104 on the gel layer 100.

Having described preferred embodiments of a support apparatus with gellayer (which are intended to be illustrative and not limiting), it isnoted that modifications and variations can be made by persons skilledin the art in light of the above teachings. It is therefore to beunderstood that changes may be made in the particular embodimentsdisclosed which are within the scope of the invention as outlined by theappended claims. Having thus described aspects of the invention, withthe details and particularity required by the patent laws, what isclaimed and desired protected by Letters Patent is set forth in theappended claims.

1. A mattress or mattress topper for supporting at least a portion ofthe body thereon, comprising a gel layer overlying at least one supportlayer in a foam material, wherein said gel layer comprises a gel havinga hardness of 4.5 kPa±1.5 kPa and a hysteresis of about 40%±10%, whereinsaid gel layer comprises a polyurethane gel facing a user, such that thegel layer confers objective and subjective comfort at a same time. 2.The apparatus according to claim 1, comprising one or more additionalsupport layers selected from the group consisting of a foam layer, aspring layer, a textile layer, a gas layer, a wood layer, a metal layer,a plastic layer, and combinations thereof.
 3. The apparatus according toclaim 1, further comprising a covering overlying said gel layer, saidcovering being selected from the group consisting of a textile layer, afilm layer, a coating layer, and a foam layer and placed above the gellayer.
 4. The apparatus according to claim 1, wherein there are noadditional support layers positioned above said gel layer.
 5. Theapparatus according to claim 1, wherein said gel layer is integrallyattached to at least one of said one or more additional support layers.6. The apparatus according to claim 1, wherein said foam is convolutedfoam.
 7. The apparatus according to claim 1, wherein said foam comprisesone or more cavities for receiving said gel layer.
 8. The apparatusaccording to claim 1, wherein said gel layer and said foam layer arechemically bonded together.
 9. The apparatus according to claim 1,wherein said gel layer has a thickness of 8 mm or more.
 10. Theapparatus according to claim 1, wherein the surface facing the usercomprises a plurality of small towers that arise from the planar surfacethereof.
 11. A mattress apparatus for supporting at least a portion ofthe body thereon, comprising: a gel layer overlying at least one supportlayers in a foam material, the gel layer including: a polyurethane gelhaving a hardness of 4.5 kPa±1.5 kPa and a hysteresis of about 40%±10%,where said polyurethane gel faces a user, such that the gel layerconfers objective and subjective comfort at a same time; and a contouredsurface of the polyurethane gel comprising tower structures.
 12. Theapparatus according to claim 11, wherein the tower structures have a toparea that is at least three times greater than a lateral area.
 13. Theapparatus according to claim 11, wherein a downward pressure on thecontoured surface cause a tri-dimensional deflection of the towerstructures, such that material displaced from the tower structuresoccupies a gap between the tower structures.
 14. The apparatus accordingto claim 11, wherein the tower structures have a rectangularcross-section.
 15. The apparatus according to claim 11, wherein thetower structures have a hexagonal cross-section.
 16. The apparatusaccording to claim 11, wherein the tower structures have a circularcross-section.
 17. The apparatus according to claim 11, wherein thetower structures are parallel curved plateaus.
 18. The apparatusaccording to claim 11, wherein the gel layer has a thickness of about8-15 mm and the tower structures are separated by a gap about 4-6 mmacross.